Surfacing - Blender Foundations: The Essential Guide to Learning Blender 2.6 - page 216

Remember that many landscape pictures have hills or other features that will obscure the actual horizon,
so make your best guess as to where it lies in the image. The good news is that camera projection is a
fairly forgiving process—a little miss here or there isn't going to be the end of the world.
With a suitable ground plane created and the camera positioned, you can begin to add (or modify) geom-
etry to match the image. Keep in mind that we are trying to match the image from the camera's point of
view, so any modeling and tweaking that is done should take place in Camera view. For the example
matte's rolling hills, I've subdivided the ground plane a number of times and pulled it into shape using
selections and PEF modeling. Figure 7.54 shows both a camera and off-axis view of the modified ground
plane. Notice how the hills in the Camera view follow the contours of those in the background image.
These same hills could have been created by adding new objects and modeling them to match the image
directly.
The large mountains in the distance begin their life as a cube, roughly positioned “behind” the ground
plane in a top view. Back in the Camera view, the shape is refined through some subdivision, loop cutting,
Figure 7.54 Low hills.